Don’t worry, we’ve been asking the same question. Out of all the beverages out there, champagne brings a lot to the table, from its complexities to its aromatics to its effervescence. Those bubbles, especially, are quite intriguing.
Champagne glasses play a crucial role in forming fine bubbles. They are designed with tiny imperfections at the bottom where CO2 gas settles, where bubbles form through a process known as nucleation. This happens due to a decrease in pressure and a change in surface tension.
Now, if chemistry and physics aren’t your thing (totally get it, who has time for that?), you might think the bubbles are just there for show. But surprise, surprise—there’s more to these captivating orbs.
And did you know champagne bubbles rise in straight lines to the surface of the glass?
Below, we’ll break down the science behind champagne bubbles, covering everything from how it’s made to the moment it lands in your glass.
The Wine-Making Process: What Is the Science Behind the Bubbles in Champagne?
The art of crafting sparkling wine can be traced back to the 17th century, attributed to the Benedictine monk Dom Pérignon. He pioneered a method called Méthode Traditionelle, fermenting wine in the bottle. It involves the addition of yeast to the wine, which triggers a second fermentation process.
That said, there are also speculations on whether or not Dom Pierre Pérignon invented sparkling wine. The first scientific paper about the Champagne production method was presented in the Royal Society of London in 1662, years before the Benedictine monk entered the monastery in the Abbey of Hautvillers.
The First Fermentation
All Champagne houses in France follow a regulation where their grapes must come from the vineyards of the Champagne region. The grapes are carefully picked for vinification.
First, they are gently pressed right after harvest. Then, comes the first fermentation (aka first alcoholic fermentation). This process often takes place in temperature-controlled stainless steel vats. Depending on the champagne producer, the wines can also be fermented in old oak barrels.
The primary fermentation is the process that introduces ethanol. It creates a still wine that is fully dry and has neutral aromas, light flavor, and high acidity. After the first fermentation, comes blending.
Champagnes are a blend of still wines and reserve wines that are made from grapes that were sourced from multiple vineyards from past and present harvests. The cellar master has the “intuition” to the blend that follows a consistent house style.
Sometimes, a champagne producer may also make sparkling wines to express the qualities of the terroir and a specific growing season instead of producing the same style each year. Meaning, that the grapes used in such particular wines are from single vineyards or vintages.
The Secondary Fermentation
After the first alcoholic fermentation, the base wine is bottled. Some are bottled with yeast and cane or beet sugar to facilitate the secondary fermentation process.
During this process, the yeast consumes the sugar which creates alcohol and a significant amount of carbon dioxide gas. Such large amounts of CO2 lead to an internal pressure of around 5 to 6 atmospheres.
Champagnes are put under pressure so the carbon dioxide gas doesn’t escape the bottle, which is why sparkling wines have a high percentage of CO2 dissolved in them.
How the Bubbles Form
As you already know, the bubbly character of champagne and other sparkling wines comes from the broken-down carbon dioxide gas that forms during the secondary fermentation process.
In unopened bottled champagne, the CO2 is balanced or equilibrium. The gas lies in the space between the wine cork and the liquid.
But when you uncork the bottle, the gas escapes and throws off that equilibrium. The dissolved CO2 then leaves the champagne in tiny (the tinier, the better) bubbles, which also restores the equilibrium. However, to reestablish equilibrium, the bottle should release gas about 6 times the amount of its volume.
The carbon dioxide bubbles are not just for a show, though. While many people love the sight of dancing gas bubbles in their flutes, these tiny orbs also enhance our perception of the champagne’s aromas and flavors.
How the taste translates on the palate is a result of a complex relationship between the amount of CO2 in the bubbles and the volatile organic compounds (VCOs) that produce the champagne aroma. Temperature, bubbling rate, and glass shape also affect its flavors.
Even with all the flavors, without those tiny bubbles, champagne would just be another typical white wine. Those little orbs are a feast for the eyes. Under the microscope, they resemble flower blossoms when inflating bubbles deform their surrounding bubbles.
The Glass Matters
It does because there are flow-mixing mechanisms within the glass.
Many glassware manufacturers and artisans explicitly design champagne glasses with nucleation sites. These sites are etched or lasered into the bottom of the goblet. However, flawed glass surfaces don’t necessarily facilitate bubbling because they may be too minimal to create an impact.
When the CO2 gas settles at the nucleation sites, it forms bubbles that rise upwards.
There’s also random bubble formation on the glass wall. Natural effervescence forms when there are microcellulose fibers in the glass. These cellulose fibers are often deposited from the air. But, they can also come from the cloth you use to wipe the champagne glass.
According to an article published by AmSci, each fiber left clings to the inner bowl through electrostatic forces. This creates an internal gas pocket when you fill the glass. The gas pockets also serve as nucleation sites.
When the bubbles form, they start as tiny beads and grow in size up to 50 micrometers. The bubbles become buoyant enough to detach from the cellulose fibers and rise to the top. And the cycle repeats.
What’s interesting about this process is that each tiny fiber can produce 30 bubbles per second. When the fizz rises to the surface, it expands due to CO2 diffusion. The larger they are, the more buoyant they become and the faster they rise to the top.
The shape of the bowl is one of the keys to effervescent champagne. Narrow flutes will give you the mousse as they concentrate more bubbles above the liquid than the wider French-style coupe glasses.
When you’re pouring champagne into a glass with a wider rim and surface area, the effervescence escapes quickly. This also means you’ll have less time to appreciate the aromas and nuances of your fizzy drinks.
Why Do Bubbles Come From the Bottom of a Glass?
Nucleation occurs slowly at the bottom of the glass bowl due to a decrease in pressure and a change in surface tension.
The CO2 molecules couldn’t escape your drink. It needs to join a few other liquid molecules to create the bubbles. Since the bubbles are randomly dancing around inside the liquid, it’s rare to have enough carbon dioxide molecules to stick together and form a bubble.
And that’s where the nucleation site comes into play.
If you’ve seen champagne flutes with tiny imperfections (nucleation sites) that are intentionally engraved or scratched into their bottom and sides, when you pour them into the glass, there is already gas trapped in them.
FYI: Glassware with artificial nucleation sites at the bottom of the goblet is widely used for Champagne tastings.
When the trapped gas collides with a CO2 molecule, the bubble they form becomes too big for the nucleation sites to hold. They have no choice but to split into two smaller bubbles. When this happens to large bubbles, you may see their baby bubbles floating behind and rise to the surface and eventually pop.
The bubbles left behind contain molecules that stick with other molecules to make bubbles. At this point, there is a continuous release of gas from the bottom to the top of the glass, with the bubbles bursting at the liquid surface, and repeating the process.
So, next time you see the cascading effect of the bubbles, thank your champagne flute. It’s a unique visual experience every time.
Why Do Champagne Bubbles Rise in Straight Lines?
The bubbles in champagne will always be in motion. But unlike many other carbonated beverages like beer whose lines veer off to the side, champagne boasts one of its bubble’s most distinct characteristics: they rise to the top in such distinct flow patterns.
So, why do the bubbles behave the way that they do?
According to an experiment done by fluid mechanics researchers from Brown University, this impressive trait of champagne bubbles boils down to surfactants or flavor molecules in sparkling wine.
These substances act as soap-like compounds that lessen the tension between the gas bubbles and the liquid. This results in stable bubble chains that smoothly rise to the top.
However, keep in mind that the size of the bubbles also affects their stability. As the size of the bubbles increases, the bubbles will form a stable chain. But even when the bubbles keep a consistent size and the sparkling wine has a higher concentration of surfactant, you’ll see the same effect.
The researchers concluded that adding surfactants and increasing bubble size are two distinct techniques for stabilizing a bubble chain.
Fizz, froth, bubble—however you call it—offers a truly amazing visual experience. Next time your champagne connoisseur friends wonder why the bubbles come from one spot, tell them that the microscopic “imperfections” in the glass bowl have a lot to do with it.
However, keep in mind that there is something more behind the dancing bubbles that only science can explain.
If you have more questions about the champagne bubbles, let us know and we’ll be happy to help. Cheers!